Assessing Risk of Emissions Generated During Illegal Waste Burning: Phytotoxicity and Bioaccumulation

Open burning of agricultural waste is a common practice in both developed and developing regions of the world, and the emissions pose serious inputs for ambient concentrations of atmospheric particulate matter (PM). In addition, when agricultural waste burning is combined with open-air burning of domestic waste such as plastic, rags, or tires, the potential risk of generating toxic emissions increases. PM samples produced via controlled burning of selected waste types were tested in our laboratory using the No. 227 OECD Guideline for the Testing of Chemicals: Terrestrial Plant Test. Comparing two recommended test species, lettuce (Lactuca sativa) and mustard (Sinapis alba), L. sativa showed significantly higher sensitivity, as treatment elucidated biomass reduction (Df = 1, F = 16.43, p = 0.000385), the biomass of the treated plants was 61.4-91.7% of the control plants. In our investigation inhibition in photosynthetic pigment activity (chlorophyll-b in lettuce (Df = 1, F = 3.609, p = 0.0701) was found. The levels of the stress enzyme peroxidase increased significantly in the case of both test species (L. sativa: Df = 1, F = 6.76, p = 0.0112; S. alba: Df = 1, F = 49.99, p = 1.63x0⁻⁹), indicating that peroxidase could be regarded as the most sensitive indicator of air pollution. The bioaccumulation pattern was also assessed, proving the risk of significant bioaccumulation of potentially toxic compounds in edible parts of the vegetables tested. Both test plants accumulated higher molecular weight PAHs in significant quantities, as the concentration of 5-ring PAHs was 43.2 μg/kg in mustard and 49.35 μg/kg in lettuce.